Research On Improvement Of Process And Ingredients On Quality For Microwave-puffed Imitation Cheese

Imitation cheese is a kind of analogue cheese. It is a smooth and uniform cheese-like product in which various kinds of edible ingredients and water were effected by heat, mechanical shear and emulsifying. Microwave-puffed imitation cheese chip is a new type of expanded products with high nutritional value and potential market. In this study drying and expansion characteristics of imitation cheese during microwave puffing were analyzed, and process conditions were optimized. And for the problem of final products with high expansion ratio, thin-wall air pocket and unhomogeneous structure, which were manufactured by casein, effect of different ingredients on microwave-puffing effect of imitation cheese was studied, formula of microwave-puffed imitation cheese chips was optimized, and ratio of products with better expansion effect was achieved in order to provide experimental and theoretical support for the practical production. The results were as follows:(1) Puffing time: Expanded time reduced with increasing microwave power. Dehydration rate was the highest and puffing time was the shortest, when thickness of imitation cheese slice was 4 mm at microwave transmission range. Puffing time extended with the increase of initial moisture content.(2) Water changes: Dehydration rates were different for the different initial conditions. When microwave power was 400 W, the process of microwave puffing was divided into the periods of accelerating dehydration, constant dehydration and decelerating dehydration. As microwave power was 600 W and 800 W, dehydration rate was increasing firstly, following decreasing, and then constant. When microwave power was 1000 W and 1200 W, dehydration rate was increasing firstly, and then decreasing. Under 4 mm initial thickness, dehydration rate was also increasing firstly, and then decreasing. Under 2 mm, 6 mm and 8 mm initial thickness, dehydration rate was increasing firstly, following decreasing, and then constant. Under 10 mm initial thickness, the snacks were in the period of accelerating dehydration, and then converted into the constant dehydration. When the moisture content was 54% and 59%, dehydration rate was increasing firstly, and then decreasing. When the moisture content was 64%, dehydration rate was firstly increasing, and then remained the constant.(3) Process were optimized by the orthogonal experiment and the three factors effect on imitation cheese puffing were moisture content > microwave power > initial thickness of imitation cheese. The best processing conditions for microwave-puffing imitation cheese were 1000 W of microwave power, 4 mm of initial thickness, 59% of moisture content.(4) Improvement of ingredients on quality: Sensory evaluation was 90.0 of the highest score as the soybean separation protein content was 12%. And expansion ratio was 180%, porosity was 23/cm2, hardness was 16.7 N and crispness was 13.3. Sensory evaluation was 84.6 of the highest score as waxy rice starch content was 9%. And expansion ratio was 190%, porosity was 28/cm2, hardness was 17.3 N and crispness was 12.7. Sensory evaluation was 84.3 of the highest score as corn starch content was 6%. And expansion ratio was 175%, porosity was 21/cm2, hardness was 13.5 N and crispness was 14.3.(5) Through the response surface methodology optimized the formula and the three factors effect on imitation cheese puffing were waxy rice starch > soybean protein > corn starch. The best formula of microwave-puffing imitation cheese with protein and starch was: 11.92% soybean protein, 10.38% waxy rice starch, 6.00% corn starch, and other added ingredients: 59%water, 8.7%casein, 1.48%citric acid sodium, 0.72% disodium hydrogen phosphate, 1.20% sodium chloride, 0.5% citric acid and 0.10% sorbic acid. The sensory score was 96.3 of this formula, The surface of these cheese chips was smooth and round, slightly yellow and crispy. Moreover the flavor of cheese and beans was appropriate.